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PI System Management Tools

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StmEng_SPH

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  • Last UpdatedSep 17, 2025
  • 1 minute read

Calculates the vapor specific entropy as a function of pressure and enthalpy—all variables expressed in English units. Use for both superheated and wet steam.

Format

StmEng_SPH(P, H)

Arguments

  • P

    Pressure of the steam in psia. The valid range is 0.08865 to 14503.77 psia.

  • H

    Computed vapor specific enthalpy in BTU/lbm. The valid range is -1.0 to 1860 BTU/lbm.

Returns

Computed vapor specific entropy in BTU/lbm/R or- Error digital state.

Sample Values

Pressure

Enthalpy

Entropy

State

300.

1526.2

1.7965

Superheated

800.

1511.4

1.6807

Superheated

1400.

1493.2

1.6095

Superheated

5000.

1364.6

1.3998

Superheated

300.

1122.

1.4183

90 % vapor

Note: Even if the input enthalpy is less than that of the saturated liquid, the function still computes the entropy by extrapolation without setting an error state.